We work on the tensor product Hilbert space \(\widetilde{\mathcal {H}}_{\mathrm {r}}:= \mathcal {H}_{\mathrm {r}}\otimes \mathcal {H}_{\mathrm {r}}\) .
We fix an inner symmetric function \(\varphi \) . As above, \(P_1\)  is the one-particle
lightlike translation. Let us recall our argument [1]}.
